* Real components of evaporator control fitted to front panel for demonstration purposes

description

The control of refrigeration units such as chiller cabinets, refrigerated display cases and freezers is a key topic in commercial refrigeration. The control aims at safeguarding a high level of food quality with simultaneous energy-efficient operation. With ET 930 the operation and programming of an industrial evaporator controller (refrigeration controller) is taught in the example of a freezer. Software simulates the freezer. The schematic depicted on the front panel aids comprehension. Lamps in the schematic indicate the operating state of the individual components. The refrigeration controller controls the temperature of the freezer via the electronic expansion valve. It also controls the air circulation fan. It provides for the defrosting of the evaporator and prevents the freezing of the freezer lid by way of a frame heating. The refrigeration controller continuously monitors the operation of the components and issues an alarm signal should errors occur. The controller is programmed via a data cable using a programming device. This allows for adjustments of the thermostat function, daytime/night-time operation, the defrosting function, energy saving functions and safety functions. In the simulation software the outside temperature is entered, the refrigerant selected and the door of the freezer opened or closed. In the "time graph" menu, the operating states of the individual components are displayed and the temperature and pressure graphs recorded.

Additional real components, such as expansion valve and pressure and temperature sensors, are used for demonstration purposes and increase the practical relevance. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

[1] experimental unit from the GUNT practical series for the training of mechatronics engineers for refrigeration [2] investigation and programming of an industrial refrigeration controller in the example of a freezer[3] simulation of the freezer by way of software[4] schematic on the front panel with lamps to indicate the operating states of the actuators[5] programming of the refrigeration controller using a programming device[6] simulated freezer with compressor, electronic expansion valve, fan, electric defrost heater for the evaporator, frame heating, pressure and temperature sensors[7] real freezer components for demonstration purposes: 1 electronic expansion valve, 1 pressure sensor, 2 temperature sensor[8] LabVIEW software for simulation via USB under Windows XP or Windows Vista

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